This excerpt was originally posted on the John Deere, Straightforward Blog October 10, 2011. You can view the original post here.
John Deere Emissions
Engine design has grown more challenging with each new tier of EPA emissions regulations. The transition from Tier 3 to Interim Tier 4 (IT4) presents non-road diesel engine manufacturers with their most significant challenge yet: IT4 regulations demand a 90 percent reduction in particulate matter (PM) and up to a 50 percent drop in nitrogen oxide (NOx) compared to Tier 3. At John Deere, we’re meeting this design challenge with a “building block” approach.
Our planning for Tier IV emissions began prior to the introduction of the first EPA-compliant engines back in 1996. We have followed a building-block approach systematically adopting technologies — such as more electronic engine controls, high-pressure fuel injection systems, 4-valve cylinder heads, variable geometry turbochargers (VGTs), more application of charge air cooled engines, and cooled exhaust gas recirculation (EGR) — to meet each successive tier of emissions regulations.
John Deere Power Systems introduced cooled EGR and VGT in 2005 with the start of Tier 3 regulations, becoming the first engine manufacturer to widely commercialize these technologies. Moving into the Interim Tier IV engine configurations, one part of our building-block approach is that the core technologies have advanced with the adoption of state-of-the-art systems. Fuel injection pressures have increased to further reduce PM, and the cooled EGR system with new “closed loop” control system precisely measures the amount of EGR required for varying speeds and loads to further reduce NOx. An important new building block for John Deere Interim Tier 4 engines is the exhaust filter, made up of a diesel oxidation catalyst (DOC) and a diesel particulate filter (DPF) to further reduce PM.
IT4 emissions requirements began January 1, 2011, for engines 174 hp and above, while the regulation effective date for engines in the 75 to 174 hp category is January 1, 2012. Despite the significant challenges posed by these new standards, John Deere engines have maintained, and in many cases improved, engine performance. Engine power levels have grown, transient response has improved, torque rise has increased and low-speed torque has been maintained.
John Deere will continue to use the building-block approach to meet future, even more demanding emissions regulations. Technologies such as cooled EGR and variable geometry turbocharging with an exhaust filter will likely be the foundation for achieving Final Tier 4 compliance. As always, we will offer the appropriate level of technology and performance to meet customer and equipment needs.